Design and Performance Analysis of a Type-III Compensator for a Buck Converter Using the Frequency Response Method

This study presents the systematic design and performance evaluation of a Type-III compensator for a non-ideal buck converter using a frequency-response-based approach and the K-factor method. The converter is modeled using state-space averaging, incorporating inductor current and capacitor voltage as state variables. Additionally, it accounts for practical non-idealities, such as capacitor ESR and supply-voltage variations. The compensator is designed to achieve the desired phase margin and enhanced closed-loop stability, considering on the open-loop characteristics. The results revealed that compared to a conventionally tuned Proportional–Integral–Derivative (PID) controller, the proposed Type-III compensator significantly improves transient and steady-state performance. Under constant-load conditions, the settling time decreases from 967.88 µs to 519.23 µs, and the overshoot from 14.11% to 10.11%. Moreover, ripple voltage is suppressed from 181.25 mVpp to 20.84 mVpp, demonstrating improved damping and voltage regulation capability. Under variable-load conditions, the compensator consistently achieves faster recovery and smaller voltage deviation during sudden load changes. Among the evaluated configurations, the 60° phase-margin design provides the best trade-off between transient speed, stability margin, and ripple suppression. Overall, the results confirm that frequency-response-based Type-III compensation constitutes an effective control strategy for non-ideal buck converters, which require high stability and low output-voltage ripple under varying operating conditions.